Python | Reading and Writing Files
  1. Writing and reading text files
  2. File existence and properties
  3. Get file information
  4. Writing and reading binary files
  5. Writing and reading JSON files
  6. Writing and reading CSV files
  1. Writing and reading text files 
    # import Path class
from pathlib import Path

# create path object - the path can be relative or absolute
path = Path('data/file.txt')

try:
  # create parent directory if it doesn't exist
  path.parent.mkdir(parents=True, exist_ok=True)

  # write content to file (create/overwrite)
  path.write_text('Hello Python', encoding='utf-8')

  # append content to file
  with path.open('a', encoding='utf-8') as f:
    f.write("\n!")

  # read content from file
  text = path.read_text(encoding='utf-8')

  print(text)
except FileNotFoundError:
  print("File not found")
except PermissionError:
  print("Permission denied")
except Exception as e:
  print(f"An error occurred: {e}")
    Output:
    Hello Python
!
  2. File existence and properties 
    from pathlib import Path

path = Path('data/file.txt')

# check if file exists
if path.exists():
  print(f'the file \'{path}\' exists')
else:
  print(f'the file \'{path}\' doesn\'t exists')
    Output:
    the file 'data/file.txt' exists
  3. Get file information 
    from pathlib import Path

path = Path('data/file.txt')

print(f'is file: {path.is_file()}')
print(f'is directory : {path.is_dir()}')
print(f'file info: {path.stat()}')
    Output:
    is file: True
is directory : False
file info: os.stat_result(st_mode=33204, st_ino=17898, st_dev=2080, st_nlink=1, st_uid=1000, st_gid=1000, st_size=14, st_atime=1748889846, st_mtime=1748889817, st_ctime=1748889817)
  4. Writing and reading binary files 
    from pathlib import Path

path = Path('data/file.bin')

path.parent.mkdir(parents=True, exist_ok=True)

# write binary data to file (create/overwrite)
path.write_bytes('Hello Python'.encode('utf-8'))

# read binary data from file
data = path.read_bytes()

print(data.decode('utf-8'))
    Output:
    Hello Python
  5. Writing and reading JSON files
    Writing/reading to/from a json file: 
    from pathlib import Path

# import json module
import json

# data
x = { 'a': 1, 'b': 2 }
y = { 'a': 11, 'b': 22 }
z = [x, y] # list of dictionaries
w = { 'r': x, 's': y, 't': z } # dictionary of list, set, and dictionaries

path = Path('data/file.json')

# write JSON to file
path.write_text(json.dumps(w, indent=2), encoding='utf-8')

# read JSON file
text_indented = path.read_text(encoding='utf-8')

print(text_indented)

text_json = json.loads(path.read_text(encoding='utf-8'))

print(list(text_json.keys())) # Output: ['r', 's', 't']

print(text_json['t'][0]['b']) # Output: 2
    Output:
    {
  "r": {
    "a": 1,
    "b": 2
  },
  "s": {
    "a": 11,
    "b": 22
  },
  "t": [
    {
      "a": 1,
      "b": 2
    },
    {
      "a": 11,
      "b": 22
    }
  ]
}
['r', 's', 't']
2
  6. Writing and reading CSV files 
    from pathlib import Path

# import csv module
import csv

data = [
  ['name', 'score'],
  ['a', 10],
  ['b', 15]
]

path = Path('data/file.csv')

# write CSV
with path.open('w', newline='', encoding='utf-8') as f:
    writer = csv.writer(f)
    writer.writerows(data)

# read CSV
with path.open('r', encoding='utf-8') as f:
  reader = csv.reader(f)
  # read headers
  headers = next(reader)
  print(f"headers: {headers}")

  for i, line in enumerate(reader, 1):
    print(f"line {i}: {dict(zip(headers, line))}")
    Output:
    headers: ['name', 'score']
line 1: {'name': 'a', 'score': '10'}
line 2: {'name': 'b', 'score': '15'}
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